A capillary fiber-based liquid metal pressure sensor

The capillary fibers can easily be prefabricated in the factory, and their production cost is reduced. Moreover, the liquid metal fibers have the advantages of good integrity, excellent electrical conductivity, inherent stretchability, easy phase transition, and can be woven or knitted into smart fabrics. To solve the problems of the complex manufacture process and low integrity of lithographic sensors, capillary fibers replace the lithographic microfluidic channel to fill liquid metal to manufacture the pressure sensor in this paper. The prefabricated fiber is poured directly to produce the flexible chip. The steel shell is employed to increase the sensor’s measuring range and to enhance its overall performance. Compression experiments on the developed sensor are conducted, and pressure-resistance curves of the developed pressure sensor are obtained. The analytical solution of the pressure for the developed sensor is derived, and the analytical results are in good agreement with the experimental data. The cyclic loading experimental result shows that the measuring range of the chip is from 0 kPa to 1900 kPa with a full-scale output value of 1644 mΩ, linearity varying from 0.14 to 1.22 mΩ kPa−1, curve coincidence of 48.2%, repeatability of 2.77% and hysteresis of 5.26%. The measuring range of the developed pressure sensor is from 0 MPa to 20 MPa with a full-scale output value of 1046 mΩ, linearity ranging from 35.63 to 70.20 mΩ MPa−1, curve coincidence of 7.5%, repeatability of 2.35% and hysteresis of 4.53%. The comparison of performance indexes shows that the capillary fiber-based chip has good measurement performance, and the introduction of steel shell further improves the measurement performance.